Note: Descriptions are shown in the official language in which they were submitted.
lZ~;879Z
DEVICE FOR T~IE PROTECTION OF THE STRINGS OF A BALL
RACKET, PARTICULARLY TENNIS RACKET
The invention relates to a device for the protection
of the strings of a ball racket, particularly tennis
racket, with a bandlike body, which is positionable in a
peripheral groove at the outside of the frame, for
tubular sleeves, which engage with radial openings in the
peripheral groove of the frame, wherein the body
10 comprises an external peripheral groove.
For the mounting of strings for stringing a tennis
racket it is known to insert eyelets into radial openings
being arranged in predetermined intervals on the frame,
through which the strings are run during stringing and
15 hereafter are put under tensile stress with an
appropriate stringing device. Therein the eyelets serve
for a more exact fixing of the position and for reducing
the collapsing stress of strings being bended and being
returned at the periphery of the frame of the tennis
20 racket and for the protection of the strings.
With these known constructions there exists the
disadvantageous fact that the parts of the strings
running along the periphery of the frame of the tennis
racket lie exposed, and it has been already proposed for
25 this purpose to provide a groove extending in peripheral
direction at the outside of the frame of the tennis
racket to guarantee some protection of the string in this
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lZ~E~792
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area. Within this peripheral groove the strings remain
nevertheless exposed so that on the one hand there
results a sight disturbing the general view of the racket
and on the other hand there exists the danger that by
touching the outer edge of the racket with pointed
objects there may take place an unintended shifting of
parts of the strings in this groove and thereby an
unintended change of the tensile stress of the strings as
well as some damaging of the strings.
From the DE-OS 20 10 450 a tennis racket of a light
metal alloy has become known, with which the strings
being positioned in a peripheral groove of the frame can
be covered by an insertable strip of ductile material.
US-PS 4 280 699 shows a racket with a metal frame with a
15 stepped U-shaped cross-section, into which a T-shaped
body of resistive synthetic material is bonded, wherein
the body comprises a groove and openings for tensioning
the strings and forms a flat surface with the frame.
Furthermore from GB-PS 212 195 U-shaped metal sleeves for
20 receiving the strings have become known with a metal-
-racket, wherein the sleeves are put into openings of the
frame. US-PS 4 220 335 shows and describes a racket with
a body being arranged in a peripheral groove on the
outside of the frame for tubular sleeves, which engage
25 with openings in the peripheral groove of the frame,
through which the strings are run for stringing. The body
is formed according to the external contour of the frame
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and the string rests on the surface of the body after
tensioning.
The invention aims at providing a device of the kind
mentioned above, which allows to define more exactly the
position of the strings at the external contour of a
tennis racket and which offers the possibility to tension
the strings in a protected and covered manner. For
solving this task the invention consists substantially
therein that the peripheral groove of the body is
10 delimited by protruding wall parts, which are moveable
towards each other by tensioning the strings being put
into the peripheral groove of the body. Because the
peripheral groove is delimited by protruding wall parts,
which are movable towards each other by tensioning the
15 strings being put into the peripheral groove of the body,
- the peripheral groove of the body is closed at least
partially so that the strings are lying completely
protected in the peripheral groove. For facilitating the
production and mounting of the racket the body consists
20 of elasticly deformable material, particularly synthetic
material.
According to a preferred embodiment of the invention
the design is such that the side of the body facing the
frame keeps free a space between the bottom of the
25 peripheral groove of the frame and the body during the
untensioned state of the strings, into which space the
body is deformable by tensioning the strings. With this
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it is for the forming of the body of elasticly deformable
material especially easily achievable that the protruding
parts of the body move towards each other after fastening
the strings and close at least partially the peripheral
groove, whereas a further improvement of the insertion of
the body into the peripheral groove of the frame can be
preferably achieved that way that the protruding wall
parts of the body are connected with lateral parts of the
body overlapping the frame.
According to the invention it is suitably proceeded
that the edges facing each other of the protruding wall
parts sit close one to another after mounting the strings
and comprise recesses or openings being in alignment
with the tubular sleeves. The recesses or openings being
15 in alignment with the tubular sleeves make easier the
mounting of the strings and the running through of them
through the tubular sleeves.
The arrangement can be made according to the
invention that before mounting the strings the parts of
20 the body overlapping the frame are inclined to the axis
of the tubular sleeves with an angle being different from
the angle between the adjacent surfaces of the frame and
the axis of the tubular sleeves. The angle which is
enclosed between the parts of the body overlapping the
25 frame before mounting the strings may be larger, for
example. According to the invention the design is
suitably such that the protruding wall parts of the
1~879Z
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peripheral groove of the body close the peripheral groove
after mounting the strings by deforming the angle of the
parts of the body overlapping the frame. Therewith
according to the invention in a cross-sectional profile
the lateral parts of the body are formed according to the
external contour of the frame.
In a preferred embodiment of the invention after
mounting the strings at least the lateral edges of the
lateral parts of the body fit closely with the frame of
10 the tennis racket, through which an aerodynamically
advantageous embodiment is produced. The tennis racket
shows a lesser drag during hitting because of this
aerodynamically advantageous embodiment and the hit can
be performed more strongly with lesser effort. Because in
15 this position the edges of the lateral parts fit closely
with the frame of the racket and the protruding wall
parts touch each other, the peripheral groove is totally
closed with the exception of the openings and the parts
of the strings lying in the peripheral groove are
20 therefore perfectly protected.
According to the invention suitably the bottom of
the peripheral groove of the body being adjacent to the
tubular sleeves comprises in a cross-sectional profile
grooves with a rounded cross-section being adjacent to
25 the protruding wall parts (12) and extending in
longitudinal direction. That way the elastic deformation
of the lateral parts of the body and also of the
9z
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protruding wall parts is improved. According to the
invention preferably the cross-section of the grooves is
at least as large as the cross-section of the strings and
between the grooves a bulging extending in longitudinal
direction and being arranged opposite the protruding wall
parts is provided for. Because of the bulging extending
between the grooves the string is inevitably directed
into one of the two grooves so that it takes up a
precisely defined position in the peripheral groove. In
lO several places it is necessary that two strings are
arranged in the peripheral groove and two strings are run
through the same tubular sleeve. In this case the second
string is put into the groove being still empty and is
placed there also in a predetermined position. Thereby it
15 is avoided that two strings are placed on top of each
other, through which the tension will become unprecise.
The strings are protected from damage and by
reducing the drag during hitting a stronger hitting is
made possible.
20The invention is described in more detail in the
following by means of an example being illustrated in the
drawing.
In it Figure 1 shows a perspective view of a part of
a frame of a tennis racket with inserted stringing,
25 partly in sectional view,
Figure 2 a modified embodiment in a section of
Figure 1 without inserted strings and
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Figure 3 the embodiment of Figure 2 after fastening
the strings, wherein for the sake of simplicity the
strings are not shown,
Figure 4 shows a somewhat modified embodiment in a
section similar to Figure 1,
Figure 5 makes clear the mounting of the strings.
In Figure 1 there is shown a frame 1 of a tennis
racket. A body 2 with a plurality of tubular sleeves 3 is
provided for, in which body is arranged a peripheral
10 groove 4 for receiving a string 5. In the representation
of Figure 1 the string 5 is already under tensile stress
so that the body 2 is pressed to the external contour 6
of the frame 1. The contour of the lateral parts 7 and 8
of the body facing the frame 1 is formed according to the
15 external contour 6 of the frame 1 so that a form-fitting
overlapping results therefrom. The peripheral groove 4
comprises at its bottom two grooves 9 and lO, which favor
the elastic deformation of the lateral parts 7 and 8. The
string 5 is in the following run through the hollow space
20 11 of the tubular sleeve and through the tubular sleeve 3
and to the opposite side of the frame.
In the fastened position shown in Figure 1 of the
strings 5 the protruding wall parts 12 of the body 2,
which delimit the peripheral groove 4, are deformed so
25 far towards each other, that the edges 13 facing each
other lie close to each other. In this way an
aerodynamically advantageous closed external contour is
126~92
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formed, which protects the strings from damage at the
same time. Eor simplifying the running through of the
strings during mounting there are openings 14 provided
for being each in alignment with the tubular sleeves 3,
which openings are delimited by recesses 15 at both sides
of the openings 14 at the edges 13 of the protruding wall
parts 12 facing each other.
In Figure 2 the body is sh~wn in unfastened state,
in which it is still put on the frame 1. The body 2 is
lO formed in one piece with the tubular sleeves and consists
of elasticly deformable material, like synthetic
material. By tensioning the strings the body is pressed
in the direction of arrow 16, as is shown in Figure 3,
- wherein the internal contour 17 of the lateral parts 7
15 and 8 fits closely with the external contour 6 of the
frame l. At the same time a movement of the edges 13 of
the protruding wall parts 12 towards each other is
caused, which is obtained thereby that the angle oG
between the lateral parts 7 and 8 and the axis 18 of the
20 tubular sleeves 3 before tensioning and shifting in
direction of arrow 16, respectively, is smaller than the
angle ~ , which is taken by the lateral parts 7 and 8
with the said axis 18 after tensioning, as it is shown in
Figure 3. The lateral parts 7 and 8 are thus folded in
25 the direction of arrows 19 during a movement of the
tubular sleeves in direction of arrow 16, from which
results the closed embodiment shown in Figure 3. The
126~792
tubular sleeves 3 are arranged in intervals on the body
2, which correspond to the bores 20 in the frame of the
tennis racket and penetrate the bores 20 during the
movement of the body in the direction of arrow 16.
In the representation of Figure 4 the body 2 being
slightly modified in its profile is put onto the frame 1
and the strings 5 are tensioned. By the strings the body
2 is pressed onto the frame 1 in the direction of arrow
16 of Figure 2. Between the frame 1 and the body 2 only a
10 slight air gap is visible. It is only essential that the
outer edges 22 fit closely with the frame 1, through
which the aerodynamically advantageous form is obtained.
Such an air gap has even favorable effects, because the
elastic deformation of the lateral parts 7 and 8 and of
15 the protruding wall parts 12 is hereby aided.
Figure 5 illustrates the mounting of the strings.
The body 2 lies in its position being pressed onto the
frame, in which position it is held by the strings being
already tensioned. The string 5 to be mounted is layed in
20 its position 5' onto the edges 13 of the protruding wall
parts 12. The string is run through the opening 14 into
the tubular sleeve 3. By tensioning the string 5 it
presses the protruding wall parts 12 downwards and the
string 5 slides from its position 5' between the
25 downwards pressed protruding wall parts into the
peripheral groove 4 of the body 2, whereafter the
~2~3752
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protruding wall parts 12 spring back to their shown
position.
At several positions, where both a longitudinal and
a transverse stringing is effected, two strings must be
put into the peripheral groove which must be both run
through the same tubular sleeve. Between the grooves 9
and 10 there is arranged a bulging 23, which is clearly
visible in Figures 3 and S. The string being first put
into the peripheral groove is directed by the bulging 23
10 into one of the two grooves 9 or 10. The second string is
equally directed by the bulging 23 into this one of the
grooves 9 or 10, in which there is not yet any string. By
this it will be achieved that the strings cannot lie on
top of each other and because of the fact that the
15 position of the strings in the peripheral groove is
precisely defined the necessary tension of the strings
can be precisely observed.
It is essential that the edges 22 of the lateral
parts 7 and 8 fit tightly with the frame of the tennis
20 racket. According to Figure 1 the lateral parts 7 and 8
fit closely with the frame 1. There may also remain an
air gap 24 between the lateral parts 7 and 8 and the
frame 1 as is shown in Figure 5.
